Posted by **Britt** on Monday, November 19, 2012 at 3:33pm.

solve: log8(w-6)=2-log8(w+15)

note: the 8 is to be little at the bottom right corner of log

- Algebra 1 -
**Steve**, Monday, November 19, 2012 at 3:47pm
since 64 = 8^2, then using base-8 logs, we have

log(w-6) = log(64)-log(w+15)

(w-6) = 64/(w+15)

(w-6)(w+15) = 64

w^2 + 9w - 154 = 0

w = 1/2 (-9±√697)

scrap the negative value (why?)

- Algebra 1 -
**Britt**, Monday, November 19, 2012 at 3:49pm
because the answer has got to be a real number which is not a negative number

- Algebra 1 -
**Britt**, Monday, November 19, 2012 at 3:53pm
how do you get 1/2 as a solution?

- Algebra 1 -
**Britt**, Monday, November 19, 2012 at 4:01pm
So technically there would be no solution right?

- Algebra 1 -
**Steve**, Monday, November 19, 2012 at 4:06pm
So, technically, the solution is

x = 1/2 (-9+√697) = 8.70

where does the 1/2 come from? Think back ... back ... back to Algebra I and the quadratic formula.

- Algebra 1 -
**Britt**, Monday, November 19, 2012 at 4:09pm
the quadratic formula is -b+-radical b^2-4ac/a

- Algebra 1 -
**Britt**, Monday, November 19, 2012 at 4:34pm
SO HOW DO YOU GET 1/2 FORM THAT?

- Algebra 1 -
**Reiny**, Monday, November 19, 2012 at 5:26pm
Britt, when Steve and I went to school, the quadratic formula used to be

(-b ± √(b^2 -4ac)/(2a) or

(1/2) (-b ± √(b^2 -4ac)/a , thus the 1/2

I was not aware of any recent changes to the formula.

## Answer This Question

## Related Questions

- Test prep - solve: log8(w-6)=2-log8(w+15) note: the 8 is to be little at the ...
- Algebra 2 - Solve the equation : 8^2x-1 = 16^x+1 i know you have to log both ...
- College Algebra - I REALLY don't understand the reason/basis/use of logarithms. ...
- Algebra - How do I start to solve -2log8(x+1) = -8? I think -2log8(x+1) is log8...
- Math - Log8 4 + log16 2 x log 27 81= x solve for x
- calc - Find the missing value: 1) log _____ = 1/2 Solve the equation, round to ...
- Algebra-Reiny please explain this - Hi Reiny, I posted this problem earlier and ...
- Log Algebra - Find the inverse of the function y=log8 x
- math - (6) Which equation is equivalent to 4^-x=8? a. log8 4=x b. logx = -4 c. ...
- Math - log(x-2) +log8 (x-4) =log6 (x-1)

More Related Questions